From 6b00769fe1502b4ad97bb327ef7ac971b208bfb5 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 19 Feb 2008 11:36:35 +0100 Subject: block: add request->raw_data_len With padding and draining moved into it, block layer now may extend requests as directed by queue parameters, so now a request has two sizes - the original request size and the extended size which matches the size of area pointed to by bios and later by sgs. The latter size is what lower layers are primarily interested in when allocating, filling up DMA tables and setting up the controller. Both padding and draining extend the data area to accomodate controller characteristics. As any controller which speaks SCSI can handle underflows, feeding larger data area is safe. So, this patch makes the primary data length field, request->data_len, indicate the size of full data area and add a separate length field, request->raw_data_len, for the unmodified request size. The latter is used to report to higher layer (userland) and where the original request size should be fed to the controller or device. Signed-off-by: Tejun Heo Cc: James Bottomley Signed-off-by: Jens Axboe --- include/linux/blkdev.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index e1888cc5b8ae..f1fe9fbf1c0e 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -216,6 +216,7 @@ struct request { unsigned int cmd_len; unsigned char cmd[BLK_MAX_CDB]; + unsigned int raw_data_len; unsigned int data_len; unsigned int sense_len; void *data; -- cgit v1.2.3-55-g7522